var array = require('./array.js');
var object = require('./object.js');
var PREFIX = 'cw-';

function join(name, mods) {
    name = PREFIX + name;
    mods = mods.map(function(mod) {
        return name + '--' + mod;
    });
    mods.unshift(name);
    return mods.join(' ');
}

function traversing(mods, conf) {
    if (!conf) {
        return;
    }
    if (typeof conf === 'string' || typeof conf === 'number') {
        mods.push(conf);
    } else if (array.isArray(conf)) {
        conf.forEach(function(item) {
            traversing(mods, item);
        });
    } else if (typeof conf === 'object') {
        object.keys(conf).forEach(function(key) {
            conf[key] && mods.push(key);
        });
    }
}

function bem(name, conf) {
    var mods = [];
    traversing(mods, conf);
    return join(name, mods);
}

module.exports = bem;
